linux-kernel - Re: [PATCH 1/4] regulator: core: If consumers don't call regulator_set

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Message-ID: <CAD=FV=UnJMGRan=pOujXFkG2oHZUFoiHvk8om+=31SVu7-y6Mg@mail.gmail.com>
Date:   Thu, 16 Aug 2018 14:03:08 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     David Collins <collinsd@...eaurora.org>
Cc:     Mark Brown <broonie@...nel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/4] regulator: core: If consumers don't call
 regulator_set_load() assume max

Hi,

On Thu, Aug 16, 2018 at 1:58 PM, David Collins <collinsd@...eaurora.org> wrote:
> Hello Doug,
>
> On 08/16/2018 01:07 PM, Doug Anderson wrote:
>> I'll work on either adding more regulator_set_load() calls to clients
>> or perhaps disabling the "regulator-allow-set-load" for a bunch of
>> rails.  David: presumably if we have a rail that we never need to be
>> on-and-in-low-power-mode can just be left in high power mode all the
>> time?  There should be no advantage of being in low power mode for a
>> regulator that is off, right?
>
> Generally speaking, yes, that is true on both points.  The only caveat is
> that there could be a minor power penalty if APPS votes for OFF+HPM and a
> non-HLOS processor votes for ON+LPM for the same regulator.  This would
> lead to an aggregated state of ON+HPM when only ON+LPM is really needed.

OK, thanks for the confirmation.  ...so if we know that this is a rail
that the non HLOS has no business dealing with then this would be a
nice simplification so we don't need to go add code to all drivers
everywhere when all they want is a simple regulator that turns on and
off.

Presumably we could also add code somewhere in Linux that would
automatically vote for LPM for a regulator that has been disabled if
we had to.

-Doug